Blender assign armature to mesh: “bone heat weighting failed to find solution for one or more bones”
The OP originally posted this in their question.


If it happened to you too and you were looking for any solution, I solved in this way:


select mesh in edit-mode;
in the bar "Mesh tools" select the voice "Remove Doubles" (that remove duplicate vertex).


Here there's a video that explain the procedure.

Another way to solve the problem would be add a modifier to the mesh:  


"Decimate" modifier.